Monopole Inflation in Brans-Dicke Theory

TL;DR

This paper explores how global monopoles behave in Brans-Dicke gravity, revealing that unlike in Einstein gravity, they eventually stabilize rather than inflate indefinitely, with implications for cosmological models.

Contribution

It extends the study of inflating topological defects to Brans-Dicke gravity and shows that monopoles stabilize instead of inflating forever, contrasting with Einstein gravity results.

Findings

Monopoles in Brans-Dicke gravity eventually shrink and stabilize.

Numerical simulations confirm the different behavior from Einstein gravity.

Cosmological constraints on model parameters are discussed.

Abstract

According to previous work, topological defects expand exponentially without an end if the vacuum expectation value of the Higgs field is of the order of the Planck mass. We extend the study of inflating topological defects to the Brans-Dicke gravity. With the help of numerical simulation we investigate the dynamics and spacetime structure of a global monopole. Contrary to the case of the Einstein gravity, any inflating monopole eventually shrinks and takes a stable configuration. We also discuss cosmological constraints on the model parameters.